1. Field of the Invention
The present invention relates to a magneto-optical disk cartridge housing a magneto-optical disk of a magnetic field modification recording system, and a magneto-optical disk apparatus in which the cartridge is put away.
2. Related Background Art
The direct overwriting type of magneto-optical disks are classified into two types: a light modulation type, and a magnetic field modulation type. The light modulation type magneto-optical disk records information by switching the magnetization direction of a magnetic layer by projection of a laser light beam modified in accordance with record signals on the magnetic layer under application of a constant auxiliary magnetic field. The magnetic field modulation type magneto-optical disk records information by switching the magnetization direction of the magnetic layer by application of an auxiliary magnetic field modified in accordance with record signals under projection of successive light or pulsed light. The light modulation type magneto-optical disk is effective in constructing a magneto-optical disk system having a high transfer rate, because of its capability of extremely high speed modulation of the laser beam. On the other hand, the magnetic field modulation type magneto-optical disk is effective in stabilization of the system and high density recording, because of the capability of stable precise pit formation without influence of skew of the disk.
As the magnetic field modulation type magneto-optical disk apparatus, information recording-reproducing apparatuses typified by minidisk apparatuses are known (called MD). FIG. 1 and FIG. 2 illustrate the main portion of such an information recording-reproducing apparatus: FIG. 1 is a plan view, and FIG. 2 is a sectional view taken on line 2xe2x80x942 in FIG. 1. Main body 32 of magneto-optical disk cartridge 30 houses magneto-optical disk 33 rotatably. Cartridge main body 32 has aperture 37A on its upper face for insertion of magnetic field modulation head 35, and has another aperture 37B on its lower face for introduction of the laser light beam emitted from optical pickup 36. Apertures 37A and 37B are closable by shutters 34A and 34B, the shutters being movable in the direction parallel to the insertion direction of magneto-optical disk cartridge 30.
Magnetic field modulation head 35 is held elastically by suspension 38 as an elastic holding means. This suspension 38 is fixed perpendicularly to the longitudinal direction of aperture 37A. The one end of suspension 38 and optical pickup 36 are fixed to support 39. Support 39 is moved perpendicularly to the direction of opening-closing of the shutters to move magnetic field modulation head 35 and optical pickup 36 together in the direction of the diameter of magneto-optical disk 33. Arrow mark 50 shows the direction of insertion of disk cartridge 30 into magneto-optical disk apparatus 31. This type of magneto-optical disk apparatus 31 can be made shorter in depth direction.
The above conventional magneto-optical disk apparatus 31, although it can be made compact in the depth direction, has a disadvantage. Specifically, in the conventional magneto-optical disk apparatus 31, the longitudinal direction of suspension 38 is perpendicular to the longitudinal direction of aperture 37A, so that suspension 38 can be made longer even though the aperture 37A has a small width. However, owing to the smaller length in the short direction (width direction) of aperture 37A, suspension 38 is naturally slanted at a larger angle as shown in FIG. 2, whereby magnetic field modulation head 35 can be affected by positional deviation of the face of magneto-optical disk 33, disadvantageously.
Suppose that suspension 38 is slanted at an angle of xcex81 to the face of magneto-optical disk 33, and the face of magneto-optical disk 33 comes to deviate by a dimension xcex94Z as shown in FIG. 3. Thereby, a core of magnetic field modulation head 35 (hereinafter also referred to as xe2x80x9chead corexe2x80x9d) will be displaced by xcex94X=xcex94Zxc3x97tan xcex81 as a lateral component. This displacement hinders precise access of the head core to a target track. In order to avoid this difficulty, the length of the head core may be made sufficiently longer to cover a larger range of the track. However, the larger length of the head core decreases magnetomotive force of the head core per unit area, resulting in a drop in the magnetic field intensity, which requires an increase in the driving current to compensate for a drop in the magnetic field. Further, the longer length of the head core causes an increase in the inductance L of the head core, an increase in impedance Z at high frequency, and an increase in power consumption and heat generation, disadvantageously.
The present invention has been made to solve the above problems of the prior art.
The present invention provides a magneto-optical disk cartridge which is less affected by deviation of the magneto-optical disk face, and can be made smaller in thickness.
The present invention also provides a magneto-otpical disk apparatus employing the above magneto-optical disk cartridge.
The magneto-optical disk cartridge of the present invention houses a magnetic field modulation type magneto-optical disk, and comprises a main body of the disk cartridge, an aperture provided on the main body of the cartridge, and a shutter for closing the aperture, wherein length W1 of a side of the main body of the cartridge in an opening and closing direction of the shutter, length W2 of a side of the main body of the cartridge in a direction perpendicular to the opening and closing direction of the shutter, length C1 of the aperture in the opening and closing direction of the shutter, and length C2 of the aperture in the direction perpendicular to the opening and closing direction of the shutter satisfy the following inequality relations:
C1 less than W1/2, C2 greater than W2/2.
The magneto-optical disk apparatus of the present invention for recording and reproducing information to or from a magneto-optical disk housed in a disk cartridge having an aperture and a shutter for closing the aperture comprises an insertion opening for inserting the cartridge, a magnetic field modulation head to be inserted into the aperture to apply modulated magnetic field-to the magneto-optical disk, and an optical pickup movable together with the magnetic field modulation head to project a light beam onto the magnetooptical disk, wherein the directions of access of the magnetic field modulation head and the optical pickup to a target track of the magneto-optical disk, the direction of insertion of the magneto-optical disk cartridge, and the direction of movement of the shutter for opening and closing are parallel to each other.